An unexpected tool makes it easier and more economical to apply conditioning to leather boots and shoes, which leaves them waterproof, comfortable and long-lasting. There are thin, watery products available for waterproofing boots, but I find them not nearly as effective as the thick brush-on variety. Instructions for those say brush on the material, let it sit, then wipe off the excess. Not all that much is absorbed into the leather, though, and what you wipe off does the boots no good and is just wasted. If you do not remove the excess, it can collect dirt. The photo shows the brush-on conditioner applied to just the toe of one boot, unheated. I use "Red Wing" brand, just because it was available at the store where I bought the Red Wing boots.
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Step 1: Gun those gunboats
The near boot has been slathered all over, and the toe is being warmed using an electric heat gun, its shiny metal tip visible at the right edge of the photo. The conditioner begins to glisten as it thins, and as the leather cools, it sucks all the conditioner into it, none is wasted. I use my Wagner Paint Stripper gun, which has a variable temperature control. The gun is set to about as warm as my bare skin can tolerate, and it is constantly kept in motion to keep from damaging the leather. I have never tried another kind of heat gun, hair drier, etc., but they might work just as well.